Electrochemical machining (ECM) has been used in the past to machine close tolerance surfaces on gas turbine engine parts, such as the airfoils and roots of blades and vanes. A problem experienced in ECM'ing such parts has been over-cutting or excessive removal of material from certain areas on the work-parts. In particular, it has been difficult to maintain tolerances for the 45.degree. pressure angle and adjacent radii on the root form of certain compressor blades as a result of over-cutting during the ECM process. There is a need to reduce over-cutting in this application so that required tolerances can be maintained on a consistent basis.
Cathode structures for ECM'ing the leading and trailing edge radii of an airfoil are disclosed in U.S. Pat. Nos. 3,849,273 and 3,970,538.
Cathodes and ECM processes for forming airfoil members are also disclosed in U.S. Pat. Nos. 3,714,017; 3,803,009; 4,052,284; 4,057,475; and 4,256,555.
Composite cathode structures for ECM'ing gears, spiral lands and other workparts are illustrated in U.S. Pat. Nos. 3,268,434; 3,429,798; and 3,499,830.
Other patents involving ECM processes and cathodes include U.S. Pat. Nos. 2,650,979; 3,288,699; 3,326,785; 3,410,781; 3,566,068 and 4,100,388.